Modified turbine engine fuel

ABSTRACT

A modified turbine engine fuel having a decreased misting tendency and a resultant decreased fire hazard connected therewith during survivable crash environments which comprises a turbine engine fuel and 0.01 to 5.0 percent by weight of a copolymer of SO2 and alpha olefins having 6-36 carbon atoms wherein the copolymer has a weight average molecular weight greater than about 1.0 X 106 and a polydispersity less than about 5.0. The method of making the modified fuel and a concentrate thereof is also disclosed.

States atet 11 1 1111 3,820,963 Moore et al. June 28, 1974 MODIFIED TURBINE ENGINE FUEL 2,976,269 3/1961 de Jong 44/76 1751 William Mwe, Lake Jackson, i233??? 3513?? 232E322? f" "41/4 1? Tex.; Robert E. Erickson, Midland, I l Mlch' Primary Examiner-Daniel E. Wyman [73] Ass1gnee: The Dow Chemical Company, Assistant Examiner-Mrs. Y. H. Smith Mldland, Mlch- Attorney, Agent, or FirmBenjamin G. Colley [22] Filed: Mar. 2, 1972 [21] App]. No.2 231,374 [57] ABSTRACT A modified turbine engine fuel having a decreased [52] U Cl Y 44/62 44/7 E 44/7 C misting tendency and a resultant decreased fire hazard 34/116 connected therewith during survivable crash environ- 51 1m. (:1 c161 1/24 which compris? a turbine engine fuel and 58 Field of Search 44/62, 76, 66 A, 7 c, 7 D, to Perm Y of a copolymer of S02 and 44/7 260/79 3 A alpha olefins havmg 6-36 carbon atoms wherein the copolymer has a weight average molecular weight greater than about 1.0 X 10 and a polydispersity less [56] Q' Zfi fZl than about 5.0. The method 0f making the modified fuel and a concentrate thereof is also disclosed. 2,652,368 9/1953 Melstrom et al 252/482 2,853,373 9/1958 Stuart 44/76 17 Claims, N0 Drawings 1 MODIFIED TURBINE ENGINE FUEL BACKGROUND OF THE INVENTION This invention relates to compositions of matter comprising a turbine engine fuel and high molecular weight alpha olefin polysulfones, a method of making the composition of matter, and a method of powering an aircraft therewith.

It is known from U.S. Pat. No. 2,853,373 (A. P. Stuart, dated Sept. 23, 1953) that relatively low molecular weight olefin polysulfones can be added to automotive fuels to reduce or eliminate the deposits in the combustion chambers. Similar low molecular weight polysulfones can be added to lubricating oils as is shown by US. Pat. No. 2,652,368 to improve the viscosity index thereof.

It is further known (from Chemical Engineering, Aug. 14, 1967, pages 108-112) that fire safe or fire resistant aircraft fuels can be made by (l) gelling the fuels with various polymers or long chain monomeric amides, and (2) making an emulsion of the fuel with water.

The patent literature is replete with patents on gelled or thickened fuels as is illustrated by US. Pat. Nos. 3,507,635; 3,527,582; and Belgium Patent No. 744,729.

The foregoing approaches to the problem of finding a suitable fire resistant aircraft fuel suffer from disadvantages such as they have reduced fluidity, i.e. very thick at low shear or static conditions and are difficult to pump, especially at the low temperatures encountered at high altitudes. The gelled or emulsified fuels tend to be immobile or flow slowly at gravity conditions leaving considerable amounts of residual fuel which cannot be pumped out and which becomes useless ballast.

SUMMARY OF THE INVENTION This invention provides turbine engine fuel which when used to power aircraft or other vehicles requiring such fuels, will provide reduced changes for fire and explosions after a collision of the vehicle with moving objects or with stationary objects such as the ground or water.

' lt has been estimated that more than percent of the deaths in airline crashes in the United States alone are caused by fire fed from ruptured fuel tanks. It is an object of this invention to provide a means to reduce this tragic loss as well as the loss of valuable equipment.

It is during these collisions that the present invention is useful since the modified fuel of this invention is dilatent in that there is an apparent viscosity increase in the shear range assumed to be encountered during survivable crash conditions. This results in a tendency for the fuel to cling together and has less tendency to break up into a mist which can be ignited by sparks or open flames usually present in a crash environment.

In contrast to the prior art, the modified turbine engine fuel of this invention does not set up, gel, or separate into two phases but remains substantially as fluid as the unmodified fuel throughout a wide temperature range.

It now has been discovered that high molecular weight olefin polysulfones of a selected side chain length or mixtures thereof and in a selected low concentration in a turbine engine fuel will impart to the fuel the unusual property of shear thickening or dilatancy under the low shear conditions estimated to be encountered in a crash landing.

As is illustrated hereinafter, the above dilatancy results in a substantial lowering of the misting tendency of the fuel under impact conditions where the fuel is released into the air. This is shown by a substantial fire reduction in a flame gun test.

For the purposes of this invention, misting is defined as the tendency of a fuel to break up into discrete droplets or mist upon impact with a solid object or by air resistance. This property is a physical phenomenon of the liquid fuel apart from the varporization characteristics thereof. I Y

Furthermore, a turbine engine fuel is defined as a liquid hydrocarbon fuel having an approximate distillation range from about l40F to about 550F. Illustrative examples of turbine fuels are diesel fuel, kerosene, jet fuels such as Jet A, Jet A-l, Jet B, JP-5 and JP-4 and the like.

The present modified fuel thus has a decreased misting tendency compared to the unmodified fuel which simply means that there is a tendency for the modified fuel to hold together in survivable crash environments and produce less of a spray mist.

A further advantage of the present invention is that I the polymers used to achieve the desired dilatancy are relatively inexpensive addition products of sulfur dioxide (S0 and an alpha olefin. At the combustion temperature of the engine used to power the vehicle, the polymer depolymerizes back into its constituent parts with the olefin being burned. Hence, the products of combustion are carbon dioxide, water, and sulfur dioxide. The S0 does not present a corrosion problem since at the high temperatures used during combustion, any water is present only as steam or heated water vapor. Hence, no sulfurous acid can be formed. Furthermore, only very small amounts of S0 are present due to the fact that the S0 copolymer is used at a low level and the S0 content of the polymer itself is low.

A still further advantage of the present invention is that high molecular weight olefin polysulfone additives are compatible with and do not interfere with the other additives commonly used in turbine engine fuels such as anti-icing compounds, anti-oxidants, corrosion inhibitors, metal deactivators, anti-static agents and the like.

Thus, the present invention is directed towards a dilatant turbine engine fuel having a decreased misting tendency and a resultant decreased fire hazard connected therewith during survivable crash environments which comprises a turbine engine fuel and an amount of a copolymer or a mixture of copolymers of S0 and alpha olefins having six to 36 carbon atoms with weight average molecular weight greater than about 1.0 X 10 sufficient to achieve greater than a 50 percent fire reduction in a flame gun test. The flame gun test is a recognized US. Government test as set forth in Example 13 hereinafter.

DETAILED DESCRIPTION as to produce a final solution of the polysulfone in the 0 fuel having 0.01 to 5.0 percent by weight. Preferably,

the concentration is 0.05 to 1.0 percent by weight. Beneficial results are also obtained when the concentration is 0.1 to 0.6 percent by weight. The high molecular weight polysulfones used in this invention have a weight average molecular weight greater than about 1.0 X to about 7 X 10 with the polydispersity in the range from about 1.5 to about 3.0.

It is well known that polydispersity is the ratio of the weight average molecular weight to the number average molecular weight and if this ratio is a relatively low number it is indicative of the presence of a. large proportion of high molecular weight polymer species relative to the proportion of low molecular weight species.

It is to be understood that the desired property of dilatancy appears to be directly related mainly to the amount of high molecular weight species in the fuel. Thus, one can obtain about the same dilatancy using a small amount (i.e. 0.01% by weight in the turbine engine fuel) of a very high molecular weight polymer having a low polydispersity as with a relatively large amount i.e., 5.0 percent of a lower molecular weight polymer having a relatively high polydispersity.

The use of alpha olefin polysulfones less than about 0.01 percent do not give the desired degree of dilatancy and amounts greater than about 5.0 percent are not economically feasible.

The final modified fuel is prepared by adding the proper weight of polysulfone to the fuel or by preparing a concentrated solution of polysulfone in the fuel and diluting it with additional fuel to the desired concentra tion.

The concentrated polysulfone solution contains less than about 30 percent by weight of the polysulfone. Preferred concentrations range from about 6 to about percent by weight. I

The polysulfone solution in a turbine engine fuel at the higher ranges are viscous, honey-like liquids which barely pour at room temperature. These concentrates are useful as a convenient source of the material which can be shipped from the point of production to the point of use and readily diluted with additional turbine engine fuel in the proper proportions to produce the final modified fuel.

As with the composition of the modified fuel, there is an inverse relationship between the amount of the polysulfone in the concentrate and its weight average molecular weight. For example, if the polysulfone has a relatively low molecular weight, one can put up to about 30 percent by weight of this into solution in a turbine engine fuel. However, if the polysulfone is of a higher molecular weight only about 15 percent will go into solution at room temperature. g h

The high molecular weight alpha olefin polysulfones useful in this invention are preferably prepared by solution polymerization or by suspension polymerization of the olefins with sulfur dioxide. 7 I

Useful alpha olefins are normal (linear) alpha monoolefins such as hexene-l, octene-l, decene-l, dodecene-l, tetradecene-l, and the like, including the higher homologues such as dotriacontaene-l, tetratriacontacne-l, and hexatriacontaene-l. These telomers are available from the Ziegler polymerization of ethylene. The normal alpha olefins can be used as pure materials or as mixtures thereof.

$ Page!!! qislefins Branched chain monomers are also useful to prepare the olefin polysulfones used in this invention. However,

in order to avoid'a problem of insolubility in the turbine engine fuel they must be blended with the alpha olefins and be used at a level less than about 10 percent by weight based on the normal alpha olefins and preferably they are used at less than 3 percent by weight. Examples of these operative branched chain monomers are 3-methyl butene-l; 2,3-dimethyl butene-l; 2,4,4-

trimethyl pentene-l; 6,6-dimethyl octene-l; decene-Z;

4,6-dimethyl heptene-l; Z-propyl-pentene-l; 3-ethyl-2- heptene; 3,3,5,5-tetramethyl hexene-l; 6,6-diethyl eicosene-l 4,4-dimethyl octadiene-l; 3,3,5,5tetraethyl hexene-l; 3,5-diisopropyl hexene-l; 3,5-di-t-butyl hexene-l; and the like.

Also useful in this invention are alpha mono-olefins commercially available from cracked waxes. These contain olefins of various chain lengths both normal and branched chain alpha olefins with a small amount The high molecular weight olefin polysulfones are preferably prepared by solution polymerization of the above olefins with S0 in specific chlorinated solvents such as chloroform, methyl chloroform, methylene chloride, mixtures thereof, or mixtures of the above with carbon tetrachloride with a minimum amount of catalyst to insure the preparation of high molecular weight species as is known in the art. This preparation is illustrated by the following examples. Further details of the process may be obtained from Ser. No. 70,538, filed Sept. 8, 1970 by W. R. Moore and R. R. Langner.

Other solvents such as benzene and liquid sulfur dioxide can be used, however, the reaction time and rate of conversion is longer and the polydispersity will be about 5 or greater.

The type of polymer formed by the foregoing techniques is illustrated by Table l in which the catalyst used was t-butyl peroxy pivalate (Lupersol l l and the olefin used was decene-l. Different catalysts will require slightly different ranges but this can be ascertained by those skilled in the art.

TABLE l Average Number Polymeri- Wt. Rate Typical Average zation Catalyst of Reaction 01. Poly- Method Conc Conv. Time Weight Dispersity suspension 0.3-0.5 low 12 hours high broad do. 0.51-09 high do. do. narrow do. 0.91-2.0 high do. medium broad do. 2 2.0 high do. med-low broad methyl chloroform solution 0.3-0.6 low 6 hours high broad do. 0.61-1.5 high do. high narrow do. l.56-3.0 high do. med. broad do. 3.0 low do. med. very broad SO solution 0.3-1.0 low 24 hours med. broad do. 1.0-3.0 med. do. med. very broad do. .0 med. do. low very broad rate of conversion: (9% per hr.)

low is from about 0.0l to about 3. medium is from about 410' about 15. high is from about 16 to about 100.

" molecular weight:

low is from about 0.10X to about 1.0Xl0. medium is from about 1.l l0 to about 5.0)(10. high is from about 5.1X10 to about 7.0)(10. polydispersity: (ratio of wt.aver. moLwt. to no. aver. mol. wt.)

narrow is from about 1.01 to about 3.0, broad is from about 3.1 to about 7.0. very broad is from about 7.1 to about EXAMPLE 1 ane) and 421 grams (568 ml. or 3.0 moles) of ndecene-l. The mixture was cooled to 10C. and S0 was added at a rate of 0.87 gram per minute for 18 hours. Then 4.21 grams (4.85 ml.) of Lupersol 11, as the catalyst, was added to the SO -Saturated mixture with paddle stirring at about 150 R.P.M. An exotherm of about 2C. was noted and the mixture became very thick about ten minutes after the catalyst addition. The mixture was further stirred for 18 hours.

After this, one liter of Jet A-l was stirred into the now viscous clear solution to make it pourable. One

half of the reactor solution was poured into each of two 4-liter beakers and further diluted was 3 ii liters of Jet A-l.

After about 5 hours of vacuum stripping, the jet fuelpolysulfone concentrate (about 10 percent by weight) was analyzed by infrared and found to be free of S0 and Chlorothene NU. it was ready for further dilution to less than 2 percent by weight to make a modified jet fuel ready for use in a turbine engine. 5 5

A sample of the polymer was analyzed by gel permeation chromatography (G.P.C.) and found to have a weight average molecular weight of 1.4 X 10 and a number average molecular weight of 0.48 X 10 with a narrow molecular weight distribution as shown by the fact that ratio of the weight average molecular weight to the number average molecular weight or polydispersity was 2.9.

EXAMPLE 2 '"aroma;amass? Example 1 using 2000 grams of ch o saad ld $5 95.95 nrqsss s-lr 25 and 3.16 grams or 0.75 percent by weight of Lupersol 11 an olefin polysulfone concentrate in 'Jet A-l was prepared having a weight average molecular weight of 1.62 X 10 and a polydispersity of 3.14.

EXAMPLE 3 A 20-gallon glass reactor fitted with an air-powered paddle stirrer, a stainless steel S0 inlet tube, and two water-cooled condensers, was charged with 60 liters of deionized water and saturated at 23C. with gaseous S0 for a four-hour period. A total of 180 mls. of Dowfax 9Nl0 (a nonylphenoxy polyethoxyethanol surfactant containing 10 moles of ethylene oxide per mole of nonyl phenol) was dispersed in the water with stirring. Immediately thereafter, 18 liters (56.7 moles) of a mixture of C C and C n-alpha olefins in approximate equal proportions and having a minimum monoolefinic content of 98.5 weight percent and a specific gravity of 0786-0795 and 120 mls. of Lupersol 11 (a mineralspirits solution containing percent by weight t-butyl peroxy pivalate) was added to the reactor with stirring speed maintained at 300 rpm. Sulfur dioxide was added continuously at a rate of 12 g/min. over the 24-hour reaction period, care being taken to maintain the temperature below about 25C. After this time, the reaction product was in the form of small particulate beads dispersed in the water. Air and nitrogen were used to purge the system to remove the final traces of free S0 The polymer was separated from the water by conventional filtration and, after being washed with deionized water to remove excess S0 and monomer, it was airdried. The finely divided beads (approx. 60 microns in diameter) were free of odor and color and had a weight average molecular weight of 1.42 X 10 as indicated by gel permeation chromatography with a polydispersity of 5.7. Yield of product was percent based on the olefin.

In order to prepare a jet fuel concentration, 552.4 grams of the above polymer was added to 8654.5 grams of Jet 'A-l to make 3 gallons of concentrate and stirred until complete dissolution takes place. This 6 percent by weight solution of the polymer in Jet A-l is diluted with further jet fuel to prepare the final useful fuel.

EXAMPLE 4 A 3-liter Pyrex resin kettle equipped with a stirrer and thermometer was set in a constant temperature water bath maintained at 31 1C. The reactor was charged with 750g. of deionized water and to this was added 250g. of n-tetradecene-l. The mixture was stirred at 250 rpm with a paddle stirrer while a steady flow of nitrogen, introduced through a dip tube below the surface of the mixture, was continued for approximately 20 minutes. Following this the S0, was introduced in the same manner (through .the dip tube) until the contents (water and olefin) of each flask was saturated with the gas. The reactor was partially shielded from light by the use of a black polyethylene cover. After saturation with S 5.0g. Lupersol 11 (a 75 percent solution of t-butyl peroxy pivalate in mineral spirits) was added as an initiator to the kettle. Immediately following, 5.0g. of a 20 percent solids latex consisting of a copolymer of 70 percent by weight N-vinyl pyrrolidone with 30 percent by weight t-butyl styrene was added as a suspending agent. The flow of S0 to the kettle was continued at about 0.85 g/min. The kettle contents immediately turned milky white.

The flow of S0 was allowed to continue for a period of about 21-22 hours and then discontinued and the kettle was purged with nitrogen for 1 it hours to remove excess sulfur dioxide. Temperature was maintained at 3032C. in the reaction mixture and stirring was continuous during the entire time.

The polymer from the kettle consisted of small sperical beads of uniform size, which were transparent after drying, and weighed 290 g., giving about 87 percent conversion. The polymer from this kettle had a weight average molecular weight of 1.35 X by G.P.C. and a polydispersity of 2.9.

A jet fuel concentrate was prepared from this polymer in the same manner as in Example 3.

EXAMPLE 5 A volume of 1040 ml. of the same mixed fraction C1640 alpha n-olefin used in Example 3 was suspended in 1560 ml. of deionized water which had been saturated with S0 at 20C. over a period of 18 hours. Prior to suspension 10.4 ml. of Lupersol 1 l was added to the oil phase (olefin) and 4.2 ml. to the water phase. To

suspend the monomer the mixture was stirred slowly at 100 rpm for about 1 minute, then rapidly at 1000 rpm for 10 minutes after which 16.6 g. of Dowfax 9N9 surfrom this polymer as in Example 3.

EXAMPLE 6 Following the procedure of Example 5, a second experiment was conducted except that 25 ppm FeSO (based on olefin) was added five minutes after addition of catalyst at the start of polymerization. This polymer had a similar high weight average molecular weight and a low polydispersity. A jet fuel concentrate is made from this polymer as in Example 3.

EXAMPLE 7 A volume of 1300 ml. of deionized water was saturated at 20C. with S0 for 18 hours. To this was added 1300 ml. of the C alpha-olefin used in Example 3 containing 9.1 ml. of Lupersol l l and the mixture was stirred at 1000 rpm. After 15 minutes 7.0 g. of sodium lauryl sulfate (Dupanol C) was added and stirring was continued at about 300 rpm. An SO pad was used during the polymerization which was continued for 24 hours. The hard white polymer beads were found to have a high weight average molecular weight and a low polydispersity. A jet fuel concentrate is made from this polymer as in Example 3.

EXAMPLE 8 A 3 liter Pyrex resin kettle equiped with a stirrer was charged with 600 grams of deionized water and saturated with SO for 5 hours at 15C. in a water bath. Then, 10 ml. of the suspending agent of Example 4 and 5 ml. of a 2 percent by weight solution of FeSO, 7H O in water was added to the kettle reactor with stirring at 150 rpm. and continued flow. The catalyst, 2 ml. (1.74 grams) of Lupersol 11, wasadded to 200 grams of hexadecene-l and this mixture was added to the kettle with continued stirring and introduction of S0 The reaction was allowed to proceed for 24 hours after which the line white beads were filtered off, water washed and air dried for 24 hours. The yield was 238 grams of the desired C olefin polysulfone having a weight average molecular weight of 1.97 X 10 and a polydispersity of 1.84.

Following the above examples, a jet fuel concentrate was prepared from this polymer.

EXAMPLE 9 The same procedures were followed as in Example 8 except that 10 ml. (8.7 gms.) of Lupersol 11 was added and the reaction was allowed to react 42 hours. The yield was 480 gms. of polymer having a weight average molecular weight of 1.64 X 10 and a polydispersity of 4.1.

EXAMPLE 10 The procedure of Example 8 was repeated with the following recipe:

1800 gms. deionized distilled water 375 gms. octadecene-l 2 mls. (1.74 gms.) Lupersol l1 5 mls. of 2 percent FeSO '7H O solution 16 mls. of the suspending agent of Example 4. The resulting yield was 258 grams of C copolymer having a weight average molecular weight of 1.35 X 10 and a polydispersity of 4.9.

EXAMPLE 1 1 A 3 liter glass resin kettle was charged with 1400 grams of deionized water and 561 grams of decene-l and the mixture was cooled to 15C. Sulfur dioxide ($0 was then added by a dip tube at a rate of 0.87 grams per minute over an 18 hour period with stirring. Lupersol 11 was then added to the water phase in an amount of 2.35 grams and 0.80 grams to the oil phase.

Then 16 grams of the copolymer suspending agent used in Example 4 was added dropwise with stirring rate at 1500 rpm. Five minutes later 0.10 gram of ferrous sulfate sesquihydrate (FeSOHH O) was added and the reaction was allowed to run for 17 hours.

The polymer beads were filtered off, water washed, and dried to obtain 750 grams of polymer or a yield of 91 percent. The polymer had a weight average molecular weight of 1.69 X by G.P.C. and a polydispersity of 2.2.

EXAMPLE 12 A concentrated solution of the above polymer of Example 11 in jet fuel was made by adding 552.4 grams cosity over a wide shear range for this polymer in Jet A-l.

TABLE II APPARENT VISCOSITY VERSUS POLYSULFONE CONCENTRATION (Brookfield Viscometer RVT, No. l Spindle) RPM Example 11 Polysulfone Concentration in Jet A-l 0.0 0.1 0.2 0.3 0.4 0.5 1.0 cps cps cps cps cps cps cps This table illustrates the apparent viscosity increasing with increased shear rate (shear thickening) using a vis- EXAMPLE 13 A flammability evaluation apparatus, developed by the Federal Aviation Administration, was employed. This is described in Report No. FAA-RD-7l-49, Aug. 1971 Small Scale Impact Tests of Crash-Safe Turbine Fuels by R. A. Russell. The apparatus comprises a large air gun, the barrel of which is 40 feet in length and 8 inches in diameter. The sample to be evaluated is placed in a cylinder of foamed polystyrene having one inch thick walls. The fuel to be evaluated in turn is placed in a double-walled one gallon polyethylene bag and placed in the foam cylinder. The fuel to be evaluated and the foam cylinder are placed in the breech of the gun. The gun is pointed in a horizontal direction at a vertically disposed 2 by 3 foot steel grating having 2 by 4 inch openings positioned about 20 feet from the muzzle of the gun. Remote from the gun and adjacent to the grating are five pans about one foot in width, 2 feet in length and 4 inches deep filled with kerosene fuel. The pans are arranged in a rectangle with one pan centrally disposed; one edge of the rectangle is parallel to and 4 feet from the grating. The rectangle is about 16 feet on the longest side and 4 feet on the other side. The closest pan is about 4 feet from the grating.

The kerosene is ignited. The foam container is then fired into the grating at a muzzle velocity of about 90 miles per hour and the fire ball of the resultant fuel spray is visually observed and rated by means of 3 spaced radiometer probes located 4 feet high on a wall parallel to and adjacent to the open pans and nine feet from the center pan. Probes A, B and C are located 4, l2 and 20 feet, respectively, from the grating.

The radiometer readings in British Thermal Units for probes A, B and C for various concentrations of the polysulfone of Example 1 l in Jet A-l fuel are given in Table 4.

TABLE IV CRASH FIRE RATING HAZARD Radiometer Reading Example 11 Polysulfone Fire cometer with low shear rates. Concentration in Jet A-l sru rtqsec. Reduction By Visual TABLE III by Weight) A B c Rating APPARENT VISCOSITY VERSUS POLYSULFONE g8 5'9 8 CONCENTRATION lb 0 0 0 0 (Rotovisco Viscometer) 0 0 0 00 Shear Example 11 Polysulfone Concentration in Jet A-l 0 0 04 0 95 Rate Sec 0.0 0.1 0.2 0.5 1.0

g 12.} 3 28 This table shows that even with very small amounts 12 (0.22 percent) of the polysulfone 1n Jet A-l about 95 116.0 1.5 4.4 5.8 5.0 16.5 percent fire reduction is achieved. 174.0 1.6 3.9 4.8 4.8 12.5 55. 349.0 1.9 3.9 3.9 4.1 11.0 X M LE 14 523.0 1.6 3.0 3.2 4.2 11.7 2438 :3-3 In order to further demonstrate the antim1sting char- 3 40:0 acteristics of the modified fuels of this invention and to This table shows the apparent viscosity decreasing as the shear rate is increased. Thus, illustrating the fact that although the modified fuel is dilatent and antimisting at the lower shear ranges assumed to be encountered in a crash landing, it also is shear thinned at higher shear ranges which reduces the problem of atomization in a gas turbine engine.

A nonabsorbent semi-gloss paper sheet is positioned under the screen at the base of the stand to cover the base area.

One drop of the modified turbine engine fuel is dropped from an eye dropper from a height of twelve feet above the screen so that it contacts the center thereof. The drop breaks into a spray pattern which is retained by the paper.

Each paper with the spray pattern is then placed in a 0.5 percent water solution of methylene blue, removed and allowed to dry. The paper turns blue except for the spray pattern which remains white.

The developed papers are then rated as compared to the pattern developed by using the polymer of Example 1 1 at a 0.25 percent concentration in Jet A-l.

Subsequent testing of these modified fuels in the flammability evaluation apparatus of Example 13 results in the visual percent fire reduction rating and the estimated B.T.U. rating.

therewith during collisions which comprises a turbine engine fuel and 0.01 to 5.0 percent by weight based on the fuel of a copolymer of S0 and alpha olefins having six to 36 carbon atoms, said copolymer having a weight average molecular weight greater than about 1.0 X and a polydispersity less than about 5.0.

8. A turbine engine fuel as set forth in claim 4 wherein the fuel is a jet fuel.

9. A turbine engine fuel as set forth in claim 4 The results are set forth in Table V. wherein the fuel 15 Jet A-1 and wherein the amount of TABLE V ANTIMISTING TEST fire Estimated reducradiometer Antition reading of Concen. misting visual middle probe Polymer in Jet A-l rating rating (BTU/ftlsec) Example I 1- 0.25 (standard) very good 95 0-] mol. wt. 0.125 good 95 0-l 159x10 0.1 good 90 0-1 P.D.* 2.1 33/67% by 0.25 good 95 0-1 wt. blend of 0.1 good 95 0l Examples 1 & 2, moLwt. 1.25 10 P.D.* 1.85 Example 9 0.5 very poor" 0 12-14 mol. wt. l.64 l0 PD. 4.l Example 10 0.5 poor 3-5 mol.wt.

135x10 PZD. 4.99 Example 8 0.25 good 80 0-1 mol. wt. 1.9?)(10 P.D."' 1.84

polydispersity this indicates that for these particular polymers the concentration sed as too lo \v Similar efficacious results are obtained with the other disclosed high molecular olefin polysulfones having the proper polydispersity.

What we claim is:

1. A turbine engine fuel with a decreased misting tendency and a resultant decreased fire hazard connected therewith during collisions which comprises a turbine engine fuel and 'an amount of a copolymer or-a mixture of copolymers of S0 and alpha olefins having six to 36 carbon atoms with a weight average molecular weight greater than about 1 X 10 sufficient to achieve greater than a 50 percent fire reduction in flame gun tests.

2. A turbine engine fuel as set forth in claim 1 wherein the amount of the copolymer used is 0.01 to 5.0 percent by weight.

3. A turbine engine fuel as set forth in claim 2 wherein the copolymer has a polydispersity less than about 5.0.

4. A turbine engine fuel with a decreased misting tendency and a resultant decreased fire hazard connected fueled with turbine engine fuel with decreased fire hazard connected therewith during survivable crash environments which comprises lrprovid ing a blend of weight 00-.

polymer of S0 and alpha olefins with the engine fuel in an amount of said copolymer sufficient to provide decreased misting during crash environments, and

2. burning said blend in said aircraft engines.

six to 36 carbon atoms, said copolymer having a weight average molecular weight greater than about 1.0 X 10 and a polydispersity less than about 5.0.

16. A liquid fuel concentrate as set forth in claim 15 wherein said copolymer is present in an amount from about 6 to about 15 percent by weight.

17. A liquid fuel concentrate as set forth in claim 15 wherein the turbine engine fuel is Jet A-l. 

2. burning said blend in said aircraft engines.
 2. A turbine engine fuel as set forth in claim 1 wherein the amount of the copolymer used is 0.01 to 5.0 percent by weight.
 3. A turbine engine fuel as set forth in claim 2 wherein the copolymer has a polydispersity less than about 5.0.
 4. A turbine engine fuel with a decreased misting tendency and a resultant decreased fire hazard connected therewith during collisions which comprises a turbine engine fuel and 0.01 to 5.0 percent by weight based on the fuel of a copolymer of SO2 and alpha olefins having six to 36 carbon atoms, said copolymer having a weight average molecular weight greater than about 1.0 X 106 and a polydispersity less than about 5.0.
 5. A turbine engine fuel as set forth in claim 4 wherein the amount of the copolymer used is 0.05 to 1.0 percent by weight based on the fuel.
 6. A turbine engine fuel as set forth in claim 4 wherein the amount of copolymer is 0.1 to 0.6 percent by weight based on the fuel.
 7. A turbine engine fuel as set forth in claim 4 wherein the copolymer is a copolymer of SO2 and an alpha olefin having 10-20 carbon atoms.
 8. A turbine engine fuel as set forth in claim 4 wherein the fuel is a jet fuel.
 9. A turbine engine fuel as set forth in claim 4 wherein the fuel is Jet A-1 and wherein the amount of the copolymer used is 0.05 to 1.0 percent by weight based on the fuel.
 10. A turbine engine fuel as set forth in claim 4 wherein the fuel is Jet A-1 and wherein the amount of the copolymer used is 0.1 to 0.6 percent by weight based on the fuel.
 11. A turbine engine fuel as set forth in claim 4 wherein the fuel is a jet fuel and wherein the copolymer is a copolymer of SO2 and an alpha n-olefin having 10-20 carbon atoms.
 12. A method for powering an aircraft having engines fueled with turbine engine fuel with decreased fire hazard connected therewith during survivable crash environments which comprises
 13. A method as set forth in claim 12 wherein the amount of copolymer used is 0.01 to 5.0 percent by weight based on the fuel.
 14. A method as set forth in claim 12 wherein the copolymer has a weight average molecular weight greater than about 1.0 X 106 and a polydispersity less than about 5.0.
 15. A liquid fuel concentrate comprising a turbine engine fuel and from aboUt 6 to about 30 percent by weight of a copolymer of SO2 and alpha olefins having six to 36 carbon atoms, said copolymer having a weight average molecular weight greater than about 1.0 X 106 and a polydispersity less than about 5.0.
 16. A liquid fuel concentrate as set forth in claim 15 wherein said copolymer is present in an amount from about 6 to about 15 percent by weight.
 17. A liquid fuel concentrate as set forth in claim 15 wherein the turbine engine fuel is Jet A-1. 